1. Field of the Invention
The present invention relates to seat reclining devices and more particularly to automotive seat reclining devices of a type which employs toothed elements for locking a seatback at a desired angular position relative to a seat cushion.
2. Description of the Prior Art
Hitherto, various types of seat reclining devices have been proposed and put into practical use particularly in the field of motor vehicles. Some are of a type which employs toothed elements for obtaining a reliable locked condition of the seatback at a desired angular position relative to a seat cushion. That is, in such type seat reclining devices, two toothed elements are employed, which are brought into a meshed engagement when it is needed to lock the seatback at the desired angular position. When it becomes to need to change the angular position of the seatback, the locked engagement between the two toothed elements is cancelled to permit a free pivotal movement of the seatback to a new desired angular position.
However, due to their inherent construction, some of the conventional seat reclining devices have failed to provide users with a satisfied operation. That is, when applied with a certain load upon supporting the back of the seat occupant, some of the seatbacks tend to make an unexpected slight back pivoting, which makes the seat occupant uncomfortable. Usually, such undesired back pivoting is caused by a play of one of the two mutually engaged toothed elements relative to the other, which is produced when the load is applied therebetween.